Liquid crystal medium and high-frequency components containing the same

ABSTRACT

The present invention relates to liquid-crystalline media comprising
         at least one compound of the formula I and   at least one compound of the formula II
 
or
   at least one compound of the formula I and   at least one compound of the formula III
 
or
   at least one compound of the formula II and   at least one compound of the formula III
 
or
   at least one compound of the formula I and   at least one compound of the formula II and   at least one compound of the formula III:       

                         
in which the parameters have the meaning indicated in Claim  1 , and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

FIELD OF THE INVENTION

The present invention relates to liquid-crystalline media and tohigh-frequency components comprising same, especially microwavecomponents for high-frequency devices, such as devices for shifting thephase of microwaves, in particular for microwave phased-array antennas.

Prior Art and Problem to be Solved

Liquid-crystalline media have a been used for some time inelectro-optical displays (liquid crystal displays—LCDs) in order todisplay information.

U.S. Pat. No. 7,183,447 discloses various laterally fluorinated,mesogenic quaterphenyl compounds.

U.S. Pat. No. 7,211,302 discloses, inter alia, liquid-crystalline mediawhich, besides polar terphenyl compounds of the formulae

also comprise small amounts of quaterphenyl compounds of the formula

in order to improve the stability of the media, in particular to UVirradiation.

Recently, however, liquid-crystalline media have also been proposed foruse in components for microwave technology, such as, for example, in DE10 2004 029 429 A and in JP 2005-120208 (A).

As a typical microwave application, the concept of the invertedmicrostrip line as described by K. C. Gupta, R. Garg, I. Bahl and P.Bhartia: Microstrip Lines and Slotlines, 2^(nd) ed., Artech House,Boston, 1996, is employed, for example, in D. Dolfi, M. Labeyrie, P.Joffre and J. P. Huignard: Liquid Crystal Microwave Phase Shifter.Electronics Letters, Vol. 29, No. 10, pp. 926-928, May 1993, N. Martin,N. Tentillier, P. Laurent, B. Splingart, F. Huert, P H. Gelin, C.Legrand: Electrically Microwave Tunable Components Using LiquidCrystals. 32^(nd) European Microwave Conference, pp. 393-396, Milan2002, or in Weil, C.: Passiv steuerbare Mikrowellenphasenschieber aufder Basis nichtlinearer Dielektrika [Passively Controllable MicrowavePhase Shifters based on Nonlinear Dielectrics], DarmstädterDissertationen D17, 2002, C. Weil, G. Lüssem, and R. Jakoby: TunableInvert-Microstrip Phase Shifter Device Using Nematic Liquid Crystals,IEEE MTT-S Int. Microw. Symp., Seattle, Wash., June 2002, pp. 367-370,together with the commercial liquid crystal K15 from Merck KGaA. C.Weil, G. Lüssem, and R. Jakoby: Tunable Invert-Microstrip Phase ShifterDevice Using Nematic Liquid Crystals, IEEE MTT-S Int. Microw. Symp.,Seattle, Wash., June 2002, pp. 367-370, achieve phase shifter qualitiesof 12°/dB at 10 GHz with a control voltage of about 40 V therewith. Theinsertion losses of the LC, i.e. the losses caused only by thepolarisation losses in the liquid crystal, are given as approximately 1to 2 dB at 10 GHz in Weil, C.: Passiv steuerbareMikrowellenphasenschieber auf der Basis nichtlinearer Dielektrika[Passively Controllable Microwave Phase Shifters based on NonlinearDielectrics], Darmstädter Dissertationen D17, 2002. In addition, it hasbeen determined that the phase shifter losses are determined primarilyby the dielectric LC losses and the losses at the waveguide junctions.T. Kuki, H. Fujikake, H. Kamoda and T. Nomoto: Microwave Variable DelayLine Using a Membrane Impregnated with Liquid Crystal. IEEE MTT-S Int.Microwave Symp. Dig. 2002, pp. 363-366, June 2002, and T. Kuki, H.Fujikake, T. Nomoto: Microwave Variable Delay Line Using Dual-FrequencySwitching-Mode Liquid Crystal. IEEE Trans. Microwave Theory Tech., Vol.50, No. 11, pp. 2604-2609, November 2002, also address the use ofpolymerised LC films and dual-frequency switching-mode liquid crystalsin combination with planar phase shifter arrangements.

A. Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548 describe, inter alia, the properties of the known singleliquid-crystalline substance K15 (Merck KGaA, Germany) at a frequency of9 GHz.

A. Gaebler, F. Goelden, S. Müller, A. Penirschke and R. Jakoby “DirectSimulation of Material Permittivites using an Eigen-SusceptibilityFormulation of the Vector Variational Approach”, 12MTC2009—International Instrumentation and Measurement TechnologyConference, Singapore, 2009 (IEEE), pp. 463-467, describe thecorresponding properties of the known liquid-crystal mixture E7(likewise Merck KGaA, Germany).

DE 10 2004 029 429 A describes the use of liquid-crystal media inmicrowave technology, inter alia in phase shifters. DE 10 2004 029 429 Ahas already investigated liquid-crystalline media with respect to theirproperties in the corresponding frequency range. In addition, itdescribes liquid-crystalline media which comprise compounds of theformulae

besides compounds of the formulae

or besides compounds of the formulae

However, these compositions are afflicted with serious disadvantages.Most of them result, besides other deficiencies, in disadvantageouslyhigh losses and/or inadequate phase shifts or inadequate materialquality.

For these applications, liquid-crystalline media having particular,hitherto rather unusual, uncommon properties, or combinations ofproperties, are required.

Novel liquid-crystalline media having improved properties are thusnecessary. In particular, the loss in the microwave region must bereduced and the material quality (η) must be improved.

In addition, there is a demand for an improvement in the low-temperaturebehaviour of the components. Both an improvement in the operatingproperties and also in the shelf life are necessary here.

There is therefore a considerable demand for liquid-crystalline mediahaving suitable properties for corresponding practical applications.

PRESENT INVENTION

Surprisingly, it has now been found that it is possible to achieveliquid-crystalline media having a suitably high Δ∈, a suitable, nematicphase range and Δn which do not have the disadvantages of the prior-artmaterials, or at least only do so to a considerably reduced extent.

These improved liquid-crystalline media in accordance with the presentinvention comprise

-   -   at least one compound of the formula I and    -   at least one compound of the formula II        or    -   at least one compound of the formula I and    -   at least one compound of the formula III        or    -   at least one compound of the formula II and    -   at least one compound of the formula III        or    -   at least one compound of the formula I and    -   at least one compound of the formula II and    -   at least one compound of the formula III

in which

-   L¹¹ denotes R¹¹ or X¹¹,-   L¹² denotes R¹² or X¹²,-   R¹¹ and R¹², independently of one another, denote H, unfluorinated    alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to    10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or    unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C    atoms, preferably alkyl or unfluorinated alkenyl,-   X¹¹ and X¹², independently of one another, denote H, F, Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C    atoms or fluorinated alkenyl, unfluorinated or fluorinated    alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7    C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or    Cl, and

-   -   independently of one another, denote

in which

-   L²¹ denotes R²¹ and, in the case where Z²¹ and/or Z²² denote    trans-CH═CH— or trans-CF═CF—, alternatively denotes X²¹,-   L²² denotes R²² and, in the case where Z²¹ and/or Z²² denote    trans-CH═CH— or trans-CF═CF—, alternatively denotes X²²,-   R²¹ and R²², independently of one another, denote H, unfluorinated    alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to    10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or    unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C    atoms, preferably alkyl or unfluorinated alkenyl,-   X²¹ and X²², independently of one another, denote F or Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or alkoxy having 1 to 7 C atoms or    fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C    atoms, or —NCS, preferably —NCS,    one of-   Z²¹ and Z²² denotes trans-CH═CH—, trans-CF═CF— or —C≡C— and the    other, independently thereof, denotes trans-CH═CH—, trans-CF═CF— or    a single bond, preferably one of them denotes —C≡C— or trans-CH═CH—    and the other denotes a single bond, and

-   -   independently of one another, denote

in which

-   L³¹ denotes R³¹ or X³¹,-   L³² denotes R³² or X³²,-   R³¹ and R³², independently of one another, denote H, unfluorinated    alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to    10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or    unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C    atoms, preferably alkyl or unfluorinated alkenyl,-   X³¹ and X³², independently of one another, denote H, F, Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C    atoms or fluorinated alkenyl, unfluorinated or fluorinated    alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7    C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or    Cl, and-   Z³¹ to Z³³, independently of one another, denote trans-CH═CH—,    trans-CF═CF—, —C≡C— or a single bond, preferably one or more of them    denotes a single bond, particularly preferably all denote a single    bond, and

-   -   independently of one another, denote

In a preferred embodiment of the present invention, theliquid-crystalline media comprise one or more compounds of the formula Iand one or more compounds of the formula III.

In a further preferred embodiment of the present invention, theliquid-crystalline media comprise one or more compounds of the formula Iand one or more compounds of the formula II.

The liquid-crystalline media in accordance with the present inventionlikewise preferably comprise one or more compounds of the formula II andone or more compounds of the formula III.

Particular preference is given in accordance with the present inventionto liquid-crystalline media which comprise one or more compounds of theformula I, one or more compounds of the formula II and one or morecompounds of the formula III.

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 15 to 90%, preferably 20 to 85% andparticularly preferably 25 to 80%, of compounds of the formula I. Theliquid-crystalline media in accordance with the present applicationpreferably comprise in total 1 to 70%, preferably 2 to 65% andparticularly preferably 3 to 60%, of compounds of the formula II.

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 0 to 60%, preferably 5 to 55% andparticularly preferably 10 to 50%, of compounds of the formula III.

In a preferred embodiment of the present invention, in which theliquid-crystalline media comprise in each case one or more compounds ofthe formulae I, II and III, the concentration of the compounds of theformula I is preferably 45 to 75%, preferably 50 to 70% and particularlypreferably 55 to 65%, the concentration of the compounds of the formulaII is preferably 1 to 20%, preferably 2 to 15% and particularlypreferably 3 to 10%, and the concentration of the compounds of theformula III is preferably 1 to 30%, preferably 5 to 25% and particularlypreferably 5 to 20%.

In a further preferred embodiment of the present invention, in which theliquid-crystalline media comprise in each case one or more compounds ofthe formulae I, II and III, the concentration of the compounds of theformula I is preferably 15 to 40%, preferably 20 to 35% and particularlypreferably 25 to 30%, the concentration of the compounds of the formulaII is preferably 10 to 35%, preferably 15 to 30% and particularlypreferably 20 to 25%, and the concentration of the compounds of theformula III is preferably 25 to 50%, preferably 30 to 45% andparticularly preferably 35 to 40%.

In a preferred embodiment of the present invention, in which theliquid-crystalline media comprise in each case one or more compounds ofthe formulae I and II, but at most 5% and preferably no compounds of theformula III, the concentration of the compounds of the formula I ispreferably 10 to 50%, preferably 20 to 40% and particularly preferably25 to 35%, the concentration of the compounds of the formula II ispreferably 40 to 70%, preferably 50 to 65% and particularly preferably55 to 60%, and the concentration of the compounds of the formula III ispreferably 1 to 4%, preferably 1 to 3% and particularly preferably 0%.

The liquid-crystalline media in accordance with the present applicationparticularly preferably comprise in total 50 to 80%, preferably 55 to75% and particularly preferably 57 to 70%, of compounds of the formulaI-1 and/or in total 5 to 70%, preferably 6 to 50% and particularlypreferably 8 to 20% of compounds selected from the group of thecompounds of the formulae I-2 and I-3.

The liquid-crystalline media in accordance with the present applicationlikewise preferably comprise in total 5 to 60%, preferably 10 to 50% andparticularly preferably 7 to 20% of compounds of the formula II.

In the case of the use of a single homologous compound, these limitscorrespond to the concentration of this homologue, which is preferably 2to 20%, particularly preferably 1 to 15%. In the case of the use of twoor more homologues, the concentration of the individual homologues islikewise preferably in each case 1 to 15%.

The compounds of the formulae I to III in each case includedielectrically positive compounds having a dielectric anisotropy ofgreater than 3, dielectrically neutral compounds having a dielectricanisotropy of less than 3 and greater than −1.5 and dielectricallynegative compounds having a dielectric anisotropy of −1.5 or less.

In a preferred embodiment of the present invention, the liquid-crystalmedium comprises one or more compounds of the formula I, preferablyselected from the group of the compounds of the formulae I-1 to I-3,preferably of the formulae I-1 and/or I-2 and/or I-3, preferably of theformulae I-1 and I-2, more preferably these compounds of the formula Ipredominantly consist, even more preferably essentially consist and veryparticularly preferably completely consist thereof:

in which the parameters have the respective meanings indicated above forformula I and preferably

-   R¹¹ denotes unfluorinated alkyl having 1 to 7 C atoms or    unfluorinated alkenyl having 2 to 7 C atoms,-   R¹² denotes unfluorinated alkyl having 1 to 7 C atoms or    unfluorinated alkenyl having 2 to 7 C atoms or unfluorinated alkoxy    having 1 to 7 C atoms,-   X¹¹ and X¹², independently of one another, denote F, Cl, —OCF₃,    —CF₃, —CN, —NCS or —SF₅, preferably F, Cl, —OCF₃ or —CN.

The compounds of the formula I-1 are preferably selected from the groupof the compounds of the formulae I-1a to I-1d, more preferably thesecompounds of the formula I-1 predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in which the parameters have the respective meanings indicated above forformula I-1 and in which

-   Y¹¹ and Y¹² each, independently of one another, denote H or F, and    preferably-   R¹¹ denotes alkyl or alkenyl, and-   X¹¹ denotes F, Cl or —OCF₃.

The compounds of the formula I-2 are preferably selected from the groupof the compounds of the formulae I-2a to I-2e and/or from the group ofthe compounds of the formulae I-2f and I-2g, more preferably thesecompounds of the formula I-2 predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

where in each case the compounds of the formula I-2a are excluded fromthe compounds of the formulae I-2b and I-2c, the compounds of theformula I-2b are excluded from the compounds of the formulae I-2c andthe compounds of the formula I-2g are excluded from the compounds of theformulae I-2f, andin which the parameters have the respective meanings indicated above forformula I-1 and in which

-   Y¹¹ and Y¹² each, independently of one another, denote H or F, and    preferably-   R¹¹ denotes alkyl or alkenyl,-   X¹¹ denotes F, Cl or —OCF₃, and preferably one of-   Y¹¹ and Y¹² denotes H and the other denotes H or F, preferably    likewise denotes H.

The compounds of the formula I-3 are preferably compounds of the formulaI-3a:

in which the parameters have the respective meanings indicated above forformula I-1 and in which preferably

-   X¹¹ denotes F, Cl, preferably F,-   X¹² denotes F, Cl or —OCF₃, preferably —OCF₃.

In an even more preferred embodiment of the present invention, thecompounds of the formula I are selected from the group of the compoundsI-1a to I-1d, preferably selected from the group of the compounds I-1cand I-1d, more preferably the compounds of the formula I predominantlyconsist, even more preferably essentially consist and very particularlypreferably completely consist thereof:

The compounds of the formula I-1a are preferably selected from the groupof the compounds I-1a-1 and I-1a-2, more preferably these compounds ofthe formula I-1a predominantly consist, even more preferably essentiallyconsist and very particularly preferably completely consist thereof:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5 and particularly preferably 3 or 7.

The compounds of the formula I-1b are preferably compounds of theformula I-1b-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-1c are preferably selected from the groupof the compounds of the formulae I-1c-1 and I-1c-4, preferably selectedfrom the group of the compounds of the formulae I-1c-1 and I-1c-2, morepreferably these compounds of the formula I-1c predominantly consist,even more preferably essentially consist and very particularlypreferably completely consist thereof:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-1d are preferably selected from the groupof the compounds of the formulae I-1d-1 and I-1d-2, preferably thecompound of the formula I-1d-2, more preferably these compounds of theformula I-1d predominantly consist, even more preferably essentiallyconsist and very particularly preferably completely consist thereof:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5.

The compounds of the formula I-2a are preferably selected from the groupof the compounds of the formulae I-2a-1 and I-2a-2, preferably thecompounds of the formula I-1a-1, more preferably these compounds of theformula I-2a predominantly consist, even more preferably essentiallyconsist and very particularly preferably completely consist thereof:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

Preferred combinations of (R¹¹ and R¹²), in particular in formulaI-2a-1, are (C_(n)H_(2n+1) and C_(m)H_(2m+1)), (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), (CH₂═CH—(CH₂)_(Z) and C_(m)H_(2m+1)),(CH₂═CH—(CH₂)_(Z) and O—C_(m)H_(2m+1)) and (C_(n)H_(2n+1) and(CH₂)_(Z)—CH═CH₂).

Preferred compounds of the formula I-2b are the compounds of the formulaI-2b-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2c are the compounds of the formulaI-2c-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2d are the compounds of the formulaI-2d-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

Preferred compounds of the formula I-2e are the compounds of the formulaI-2e-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R¹¹ and R¹²) here is, in particular,(C_(n)H_(2n+1) and O—C_(m)H_(2m+1)).

Preferred compounds of the formula I-2f are the compounds of the formulaI-2f-1.

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R¹¹ and R¹²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

Preferred compounds of the formula I-2g are the compounds of the formulaI-2g-1:

in which

-   R¹¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R¹² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R¹¹ and R¹²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The compounds of the formula II are preferably selected from the groupof the compounds of the formulae II-1 to II-4, more preferably thesecompounds of the formula II predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in which

-   Z²¹ and Z²² denote trans-CH═CH— or trans-CF═CF—, preferably    trans-CH═CH—, and the other parameters have the meaning given above    under formula II, and preferably-   R²¹ and R²², independently of one another, denote H, unfluorinated    alkyl or alkoxy having 1 to 7 C atoms or unfluorinated alkenyl    having 2 to 7 C atoms,-   X²² denotes F, Cl, —CN or —NCS, preferably —NCS,    and one of

-   -   and the others, independently of one another, denote

-   R²¹ denotes C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² denotes C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂,    and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2,    and where the compounds of the formula II-2 are excluded from the    compounds of the formula II-1.

The compounds of the formula II-1 are preferably selected from the groupof the compounds of the formulae II-1a and II-1b, preferably selectedfrom the group of the compounds of the formula II-1a, more preferablythese compounds of the formula II-1 predominantly consist, even morepreferably essentially consist and very particularly preferablycompletely consist thereof:

in which

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R²¹ and R²²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)) in the case of formula II-1a and particularly preferably(C_(n)H_(2n+1) and O—C_(m)H_(2m+1)) in the case of formula II-1b.

The compounds of the formula II-2 are preferably compounds of theformula II-2a:

in which

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R²² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R²¹ and R²²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The compounds of the formula II-3 are preferably compounds of theformula II-3a:

in which the parameters have the meanings indicated above for formulaII-3 and preferably

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1)) in which-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5, and-   X²² denotes —F, —Cl, —OCF₃, —CN or —NCS, particularly preferably    —NCS.

The compounds of the formula II-4 are preferably compounds of theformula II-4a:

in which the parameters have the meanings indicated above for formulaII-4 and preferably

-   R²¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5, and-   X²² denotes —F, —Cl, —OCF₃, —CN or —NCS, particularly preferably    —NCS.

Further preferred compounds of the formula II are the compounds of thefollowing formulae:

in which

-   n denotes an integer in the range from 0 to 7, preferably in the    range from 1 to 5.

The compounds of the formula III are preferably selected from the groupof the compounds of the formulae III-1 to III-7, more preferably thesecompounds of the formula III predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

where the compounds of the formula III-5 are excluded from the compoundsof the formula III-6, andin which the parameters have the respective meanings indicated above forformula I and preferably

-   R³¹ denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C    atoms, or unfluorinated alkenyl having 2 to 7 C atoms,-   R³² denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C    atoms, or unfluorinated alkenyl having 2 to 7 C atoms, and-   X³² denotes F, Cl, or —OCF₃, preferably F, and particularly    preferably-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The compounds of the formula III-1 are preferably selected from thegroup of the compounds of the formulae III-1a to III-1d, more preferablythese compounds of the formula III-1 predominantly consist, even morepreferably essentially consist and very particularly preferablycompletely consist thereof:

in which X³² has the meaning given above for formula III-2 and

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), in which-   n denotes 1 to 7, preferably 2 to 6, particularly preferably 2, 3 or    5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2, and-   X³² preferably denotes F.

The compounds of the formula III-2 are preferably selected from thegroup of the compounds of the formulae III-2a and III-2b, preferably ofthe formula III-2a, more preferably these compounds of the formula III-2predominantly consist, even more preferably essentially consist and veryparticularly preferably completely consist thereof:

in which

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-3 are preferably compounds of theformula III-3a:

in which

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-4 are preferably compounds of theformula III-4a:

in which

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-5 are preferably selected from thegroup of the compounds of the formulae III-5a and III-5b, preferably ofthe formula III-5a, more preferably these compounds of the formula III-5predominantly consist, even more preferably essentially consist and veryparticularly preferably completely consist thereof:

in which

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula III-6 are preferably selected from thegroup of the compounds of the formulae III-6a and III-6b, morepreferably these compounds of the formula III-6 predominantly consist,even more preferably essentially consist and very particularlypreferably completely consist thereof:

in which

-   R³¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R³² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R³¹ and R³²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The media in accordance with the present invention optionally compriseone or more compounds of the formula IV

in which

-   R⁴¹ and R⁴², independently of one another, denote H, unfluorinated    alkyl or alkoxy having 1 to 15, preferably 3 to 10, C atoms or    unfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 15,    preferably 3 to 10, C atoms, preferably unfluorinated alkyl or    alkenyl,    one of-   Z⁴¹ and Z⁴² denotes trans-CH═CH—, trans-CF═CF— or —C≡C— and the    other denotes, independently thereof, trans-CH═CH—, trans-CF═CF— or    a single bond, preferably one of them denotes —C≡C— or trans-CH═CH—    and the other denotes a single bond, and

-   -   independently of one another, denote

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 0 to 40%, preferably 0 to 30% andparticularly preferably 5 to 25%, of compounds of the formula IV.

The compounds of the formulae IV are preferably selected from the groupof the compounds of the formulae IV-1 to IV-3, more preferably thesecompounds of the formula IV predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in whichone of

-   Y⁴¹ and Y⁴² denotes H and the other denotes H or F, and-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formulae IV-1 are preferably selected from thegroup of the compounds of the formulae IV-1a to IV-1c, more preferablythese compounds of the formula IV-1 predominantly consist, even morepreferably essentially consist and very particularly preferablycompletely consist thereof:

in which

-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andC_(m)H_(2m+1)).

The compounds of the formula IV-2 are preferably compounds of theformula IV-2a:

in which

-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)), C_(n)H_(2n+1) and O—C_(m)H_(2m+1))and (CH₂═CH—(CH₂)_(Z) and C_(m)H_(2m+1)), particularly preferably(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

The compounds of the formula IV-3 are preferably compounds of theformula IV-3a:

in which

-   R⁴¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁴² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁴¹ and R⁴²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The media in accordance with the present invention optionally compriseone or more compounds of the formula V

in which

-   L⁵¹ denotes R⁵¹ or X⁵¹,-   L⁵² denotes R⁵² or X⁵²,-   R⁵¹ and R⁵², independently of one another, denote H, unfluorinated    alkyl or alkoxy having 1 to 15, preferably 3 to 10, C atoms or    unfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 15,    preferably 3 to 10, C atoms, preferably unfluorinated alkyl or    alkenyl,-   X⁵¹ and X⁵², independently of one another, denote H, F, Cl, —CN,    —NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C    atoms or fluorinated alkenyl, unfluorinated or fluorinated    alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7    C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or    Cl, and-   Z⁵¹ to Z⁵³, independently of one another, denote trans-CH═CH—,    trans-CF═CF—, —C≡C— or a single bond, preferably one or more of them    denotes a single bond, and particularly preferably all denote a    single bond,

-   -   independently of one another, denote

The compounds of the formula V are preferably selected from the group ofthe compounds of the formulae V-1 to V-3, more preferably thesecompounds of the formula V predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in which the parameters have the respective meanings indicated aboveunder formula V and preferablyone of

andin which

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁵¹ and R⁵²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

The liquid-crystalline media in accordance with the present applicationpreferably comprise in total 5 to 30%, preferably 10 to 25% andparticularly preferably 15 to 20%, of compounds of the formula V.

The compounds of the formula V-1 are preferably selected from the groupof the compounds of the formulae V-1a to V-1e, more preferably thesecompounds of the formula V-1 predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in which the parameters have the meaning given above and preferably

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1), and-   n denotes an integer in the range from 0 to 15, preferably in the    range from 1 to 7 and particularly preferably 1 to 5, and-   X⁵² preferably denotes F or Cl.

The compounds of the formula V-2 are preferably selected from the groupof the compounds of the formulae V-2a and V-2b, more preferably thesecompounds of the formula V-2 predominantly consist, even more preferablyessentially consist and very particularly preferably completely consistthereof:

in which

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combination of (R⁵¹ and R⁵²) here is, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)).

The compounds of the formula V-3 are preferably compounds of theformulae V-3a and V-3b:

in which

-   R⁵¹ has the meaning indicated above and preferably denotes    C_(n)H_(2n+1) or CH₂═CH—(CH₂)_(Z), and-   R⁵² has the meaning indicated above and preferably denotes    C_(m)H_(2m+1) or O—C_(m)H_(2m+1) or (CH₂)_(Z)—CH═CH₂, and in which-   n and m, independently of one another, denote an integer in the    range from 0 to 15, preferably in the range from 1 to 7 and    particularly preferably 1 to 5, and-   z denotes 0, 1, 2, 3 or 4, preferably 0 or 2.

The preferred combinations of (R⁵¹ and R⁵²) here are, in particular,(C_(n)H_(2n+1) and C_(m)H_(2m+1)) and (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)), particularly preferably (C_(n)H_(2n+1) andO—C_(m)H_(2m+1)).

In a preferred embodiment of the present invention, the medium comprisesone or more dielectrically positive compounds of the formula I-1 havinga dielectric anisotropy of greater than 3.

The medium preferably comprises one or more dielectrically neutralcompounds of the formula I-2 having a dielectric anisotropy in the rangefrom more than −1.5 to 3.

In a preferred embodiment of the present invention, the medium comprisesone or more compounds of the formula II.

In a further preferred embodiment of the present invention, the mediumcomprises one or more compounds of the formula III.

The liquid-crystalline media in accordance with the present inventionpreferably comprise 10% or less, preferably 5% or less, particularlypreferably 2% or less, very particularly preferably 1% or less, and inparticular absolutely no compound having only two or fewer five- and/orsix-membered rings.

The definitions of the abbreviations (acronyms) are likewise indicatedbelow in Table D or are evident from Tables A to C.

The liquid-crystalline media in accordance with the present inventionpreferably comprise, more preferably predominantly consist of, even morepreferably essentially consist of and very preferably completely consistof compounds selected from the group of the compounds of the formulae Ito V, preferably I to IV and very preferably I to III and/or V.

In this application, comprise in connection with compositions means thatthe entity in question, i.e. the medium or the component, comprises thecomponent or components or compound or compounds indicated, preferablyin a total concentration of 10% or more and very preferably 20% or more.

In this connection, predominantly consist of means that the entity inquestion comprises 55% or more, preferably 60% or more and verypreferably 70% or more of the component or components or compound orcompounds indicated.

In this connection, essentially consist of means that the entity inquestion comprises 80% or more, preferably 90% or more and verypreferably 95% or more of the component or components or compound orcompounds indicated.

In this connection, completely consist of means that the entity inquestion comprises 98% or more, preferably 99% or more and verypreferably 100.0% of the component or components or compound orcompounds indicated.

Other mesogenic compounds which are not explicitly mentioned above canoptionally and advantageously also be used in the media in accordancewith the present invention. Such compounds are known to the personskilled in the art.

The liquid-crystal media in accordance with the present inventionpreferably have a clearing point of 90° C. or more, more preferably 100°C. or more, still more preferably 120° C. or more, particularlypreferably 150° C. or more and very particularly preferably 170° C. ormore.

The nematic phase of the media in accordance with the inventionpreferably extends at least from 20° C. or less to 90° C. or more,preferably up to 100° C. or more, more preferably at least from 0° C. orless to 120° C. or more, very preferably at least from −10° C. or lessto 140° C. or more and in particular at least from −20° C. or less to150° C. or more.

The Δ∈ of the liquid-crystal medium in accordance with the invention, at1 kHz and 20° C., is preferably 1 or more, more preferably 2 or more andvery preferably 3 or more.

The Δn of the liquid-crystal media in accordance with the presentinvention, at 589 nm (Na^(D)) and 20° C., is preferably in the rangefrom 0.200 or more to 0.90 or less, more preferably in the range from0.250 or more to 0.90 or less, even more preferably in the range from0.300 or more to 0.85 or less and very particularly preferably in therange from 0.350 or more to 0.800 or less.

In a first preferred embodiment of the present application, the Δn ofthe liquid-crystal media in accordance with the present invention ispreferably 0.50 or more, more preferably 0.55 or more.

In accordance with the present invention, the individual compounds ofthe formula I are preferably used in a total concentration of 10% to70%, more preferably 20% to 60%, even more preferably 30% to 50% andvery preferably 25% to 45% of the mixture as a whole.

The compounds of the formula II are preferably used in a totalconcentration of 1% to 20%, more preferably 1% to 15%, even morepreferably 2% to 15% and very preferably 3% to 10% of the mixture as awhole.

The compounds of the formula III are preferably used in a totalconcentration of 1% to 60%, more preferably 5% to 50%, even morepreferably 10% to 45% and very preferably 15% to 40% of the mixture as awhole.

The liquid-crystal media preferably comprise, preferably predominantlyconsist of and very preferably completely consist of in total 50% to100%, more preferably 70% to 100% and very preferably 80% to 100% and inparticular 90% to 100% of the compounds of the formulae I, II, III, IVand V, preferably of the formulae I, III, IV and V, more preferably ofthe formulae I, II, III, IV and/or VI.

In the present application, the expression dielectrically positivedescribes compounds or components where Δ∈>3.0, dielectrically neutraldescribes those where −1.5≦Δ∈≦3.0 and dielectrically negative describesthose where Δ∈<−1.5. Δ∈ is determined at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of the respective compound is determinedfrom the results of a solution of 10% of the respective individualcompound in a nematic host mixture. If the solubility of the respectivecompound in the host mixture is less than 10%, the concentration isreduced to 5%. The capacitances of the test mixtures are determined bothin a cell having homeotropic alignment and in a cell having homogeneousalignment. The cell thickness of both types of cells is approximately 20μm. The voltage applied is a rectangular wave having a frequency of 1kHz and an effective value of typically 0.5 V to 1.0 V, but it is alwaysselected to be below the capacitive threshold of the respective testmixture.

Δ∈ is defined as (∈_(∥)−∈_(⊥)), while ∈_(ave.) is (∈_(∥)+2∈_(⊥))/3.

The host mixture used for dielectrically positive compounds is mixtureZLI-4792 and that used for dielectrically neutral and dielectricallynegative compounds is mixture ZLI-3086, both from Merck KGaA, Germany.The absolute values of the dielectric constants of the compounds aredetermined from the change in the respective values of the host mixtureon addition of the compounds of interest. The values are extrapolated toa concentration of the compounds of interest of 100%.

Components having a nematic phase at the measurement temperature of 20°C. are measured as such, all others are treated like compounds.

The expression threshold voltage in the present application refers tothe optical threshold and is quoted for 10% relative contrast (V₁₀), andthe expression saturation voltage refers to the optical saturation andis quoted for 90% relative contrast (V₉₀), in both cases unlessexpressly stated otherwise. The capacitive threshold voltage (V₀), alsocalled the Freedericks threshold (V_(Fr)), is only used if expresslymentioned.

The parameter ranges indicated in this application all include the limitvalues, unless expressly stated otherwise.

The different upper and lower limit values indicated for various rangesof properties in combination with one another give rise to additionalpreferred ranges.

Throughout this application, the following conditions and definitionsapply, unless expressly stated otherwise. All concentrations are quotedin percent by weight and relate to the respective mixture as a whole,all temperatures are quoted in degrees Celsius and all temperaturedifferences are quoted in differential degrees. All physical propertiesare determined in accordance with “Merck Liquid Crystals, PhysicalProperties of Liquid Crystals”, Status November 1997, Merck KGaA,Germany, and are quoted for a temperature of 20° C., unless expresslystated otherwise. The optical anisotropy (Δn) is determined at awavelength of 589.3 nm. The dielectric anisotropy (Δ∈) is determined ata frequency of 1 kHz. The threshold voltages, as well as all otherelectro-optical properties, are determined using test cells produced atMerck KGaA, Germany. The test cells for the determination of Δ∈ have acell thickness of approximately 20 μm. The electrode is a circular ITOelectrode having an area of 1.13 cm² and a guard ring. The orientationlayers are SE-1211 from Nissan Chemicals, Japan, for homeotropicorientation (∈_(∥)) and polyimide AL-1054 from Japan Synthetic Rubber,Japan, for homogeneous orientation (∈_(⊥)). The capacitances aredetermined using a Solatron 1260 frequency response analyser using asine wave with a voltage of 0.3 V_(rms). The light used in theelectro-optical measurements is white light. A set-up using acommercially available DMS instrument from Autronic-Melchers, Germany,is used here. The characteristic voltages have been determined underperpendicular observation. The threshold (V₁₀), mid-grey (V₅₀) andsaturation (V₉₀) voltages have been determined for 10%, 50% and 90%relative contrast, respectively.

The liquid-crystalline media are investigated with respect to theirproperties in the microwave frequency range as described in A.Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548.

Compare in this respect also A. Gaebler, F. Gölden, S. Müller, A.Penirschke and R. Jakoby “Direct Simulation of Material Permittivites .. . ”, 12MTC 2009—International Instrumentation and MeasurementTechnology Conference, Singapore, 2009 (IEEE), pp. 463-467, and DE 102004 029 429 A, in which a measurement method is likewise described indetail.

The liquid crystal is introduced into a polytetrafluoroethylene (PTFE)capillary. The capillary has an internal radius of 180 μm and anexternal radius of 350 μm. The effective length is 2.0 cm. The filledcapillary is introduced into the centre of the cavity with a resonancefrequency of 30 GHz. This cavity has a length of 6.6 mm, a width of 7.1mm and a height of 3.6 mm. The input signal (source) is then applied,and the result of the output signal is recorded using a commercialvector network analyser.

The change in the resonance frequency and the Q factor between themeasurement with the capillary filled with the liquid crystal and themeasurement without the capillary filled with the liquid crystal is usedto determine the dielectric constant and the loss angle at thecorresponding target frequency by means of equations 10 and 11 in A.Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R.Jakoby: “Cavity Perturbation Method for Characterization of LiquidCrystals up to 35 GHz”, 34^(th) European Microwave Conference—Amsterdam,pp. 545-548, as described therein.

The values for the components of the properties perpendicular andparallel to the director of the liquid crystal are obtained by alignmentof the liquid crystal in a magnetic field. To this end, the magneticfield of a permanent magnet is used. The strength of the magnetic fieldis 0.35 tesla. The alignment of the magnets is set correspondingly andthen rotated correspondingly through 90°.

Preferred components are phase shifters, varactors, wireless and radiowave antenna arrays, matching circuit adaptive filters and others.

In the present application, the term compounds is taken to mean both onecompound and a plurality of compounds, unless expressly statedotherwise.

The liquid-crystal media according to the invention preferably havenematic phases of in each case at least from −20° C. to 80° C.,preferably from −30° C. to 85° C. and very particularly preferably from−40° C. to 100° C. The phase particularly preferably extends to 120° C.or more, preferably to 140° C. or more and very particularly preferablyto 180° C. or more. The expression have a nematic phase here means onthe one hand that no smectic phase and no crystallisation are observedat low temperatures at the corresponding temperature and on the otherhand that no clearing occurs on heating from the nematic phase. Theinvestigation at low temperatures is carried out in a flow viscometer atthe corresponding temperature and checked by storage in test cellshaving a layer thickness of 5 μm for at least 100 hours. At hightemperatures, the clearing point is measured in capillaries byconventional methods.

Furthermore, the liquid-crystal media according to the invention arecharacterised by high optical anisotropy values. The birefringence at589 nm is preferably 0.20 or more, particularly preferably 0.25 or more,particularly preferably 0.30 or more, particularly preferably 0.40 ormore and very particularly preferably 0.45 or more. In addition, thebirefringence is preferably 0.80 or less.

The liquid crystals employed preferably have a positive dielectricanisotropy. This is preferably 2 or more, preferably 4 or more,particularly preferably 6 or more and very particularly preferably 10 ormore.

Furthermore, the liquid-crystal media according to the invention arecharacterised by high anisotropy values in the microwave range. Thebirefringence at about 8.3 GHz is, for example, preferably 0.14 or more,particularly preferably 0.15 or more, particularly preferably 0.20 ormore, particularly preferably 0.25 or more and very particularlypreferably 0.30 or more. In addition, the birefringence is preferably0.80 or less.

The material quality η(μ-waves)/tan(δ) of the preferred liquid-crystalmaterials is 5 or more, preferably 6 or more, preferably 8 or more,preferably 10 or more, preferably 15 or more, preferably 17 or more,particularly preferably 20 or more and very particularly preferably 25or more.

The preferred liquid-crystal materials have phase shifter qualities of15°/dB or more, preferably 20°/dB or more, preferably 30°/dB or more,preferably 40°/dB or more, preferably 50°/dB or more, particularlypreferably 80°/dB or more and very particularly preferably 100°/dB ormore.

In some embodiments, however, liquid crystals having a negative value ofthe dielectric anisotropy can also advantageously be used.

The liquid crystals employed are either individual substances ormixtures. They preferably have a nematic phase.

The term “alkyl” preferably encompasses straight-chain and branchedalkyl groups having 1 to 15 carbon atoms, in particular thestraight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl andheptyl. Groups having 2 to 10 carbon atoms are generally preferred.

The term “alkenyl” preferably encompasses straight-chain and branchedalkenyl groups having 2 to 15 carbon atoms, in particular thestraight-chain groups. Particularly preferred alkenyl groups are C₂- toC₇-1E-alkenyl, C₄- to C₇-3E-alkenyl, C₅- to C₇-4-alkenyl, C₆- toC₇-5-alkenyl and C₇-6-alkenyl, in particular C₂- to C₇-1E-alkenyl, C₄-to C₇-3E-alkenyl and C₅- to C₇-4-alkenyl. Examples of further preferredalkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl,1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl,3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl,6-heptenyl and the like. Groups having up to 5 carbon atoms aregenerally preferred.

The term “fluoroalkyl” preferably encompasses straight-chain groupshaving a terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl,3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and7-fluoroheptyl. However, other positions of the fluorine are notexcluded.

The term “oxaalkyl” or “alkoxyalkyl” preferably encompassesstraight-chain radicals of the formula C_(n)H_(2n+1)—O—(CH₂)_(m), inwhich n and m each, independently of one another, denote 1 to 10.Preferably, n is 1 and m is 1 to 6.

Compounds containing a vinyl end group and compounds containing a methylend group have low rotational viscosity.

In the present application, both high-frequency technology andhyper-frequency technology denote applications having frequencies in therange from 1 MHz to 1 THz, preferably from 1 GHz to 500 GHz, morepreferably 2 GHz to 300 GHz, particularly preferably from about 5 to 150GHz.

The liquid-crystal media in accordance with the present invention maycomprise further additives and chiral dopants in the usualconcentrations. The total concentration of these further constituents isin the range from 0% to 10%, preferably 0.1% to 6%, based on the mixtureas a whole. The concentrations of the individual compounds used are eachpreferably in the range from 0.1% to 3%. The concentration of these andsimilar additives is not taken into consideration when quoting thevalues and concentration ranges of the liquid-crystal components andliquid-crystal compounds of the liquid-crystal media in thisapplication.

The liquid-crystal media according to the invention consist of aplurality of compounds, preferably 3 to 30, more preferably 4 to 20 andvery preferably 4 to 16 compounds. These compounds are mixed in aconventional manner. In general, the desired amount of the compound usedin the smaller amount is dissolved in the compound used in the largeramount. If the temperature is above the clearing point of the compoundused in the higher concentration, it is particularly easy to observecompletion of the dissolution process. It is, however, also possible toprepare the media in other conventional ways, for example usingso-called pre-mixes, which can be, for example, homologous or eutecticmixtures of compounds, or using so-called “multibottle” systems, theconstituents of which are themselves ready-to-use mixtures.

All temperatures, such as, for example, the melting point T(C,N) orT(C,S), the transition from the smectic (S) to the nematic (N) phaseT(S,N) and the clearing point T(N,I) of the liquid crystals, are quotedin degrees Celsius. All temperature differences are quoted indifferential degrees.

In the present invention and especially in the following examples, thestructures of the mesogenic compounds are indicated by means ofabbreviations, also referred to as acronyms. In these acronyms, thechemical formulae are abbreviated as follows using Tables A to C below.All groups C_(n)H_(2n+1), C_(m)H_(2m+1) and C_(l)H_(2l+1) orC_(n)H_(2n−1), C_(m)H_(2m−1) and C_(l)H_(2l−1) denote straight-chainalkyl or alkenyl, preferably 1-E-alkenyl, respectively, in each casehaving n, m or l C atoms. Table A lists the codes used for the ringelements of the core structures of the compounds, while Table B showsthe linking groups. Table C gives the meanings of the codes for theleft-hand or right-hand end groups. Table D shows illustrativestructures of compounds with their respective abbreviations.

TABLE A Ring elements

TABLE B Linking groups E —CH₂CH₂— Z —CO—O— V —CH═CH— ZI —O—CO— X —CF═CH—O —CH₂—O— XI —CH═CF— OI —O—CH₂— B —CF═CF— Q —CF₂—O— T —C≡C— QI —O—CF₂— W—CF₂CF₂—

TABLE C End groups Left-hand side Right-hand side Use alone -n-C_(n)H_(2n+1)— -n —C_(n)H_(2n+1) -nO- C_(n)H_(2n+1)—O— -nO—O—C_(n)H_(2n+1) -V- CH₂═CH— -V —CH═CH₂ -nV- C_(n)H_(2n+1)—CH═CH— -nV—C_(n)H_(2n)—CH═CH₂ -Vn- CH₂═CH—C_(n)H_(2n+1)— -Vn —CH═CH—C_(n)H_(2n+1)-nVm- C_(n)H_(2n+1)—CH═CH—C_(m)H_(2m)— -nVm—C_(n)H_(2n)—CH═CH—C_(m)H_(2m+1) -N- N≡C— -N —C≡N -S- S═C═N— -S —N═C═S-F- F— -F —F -CL- Cl— -CL —Cl -M- CFH₂— -M —CFH₂ -D- CF₂H— -D —CF₂H -T-CF₃— -T —CF₃ -MO- CFH₂O— -OM —OCFH₂ -DO- CF₂HO— -OD —OCF₂H -TO- CF₃O—-OT —OCF₃ -OXF- CF₂═CH—O— -OXF —O—CH≡CF₂ -A- H—C≡C— -A —C≡C—H -nA-C_(n)H_(2n+1)—C≡C— -An —C≡C—C_(n)H_(2n+1) -NA- N≡C—C≡C— -AN —C≡C—C≡N Usetogether with others -...A...- —C≡C— -...A... —C≡C— -...V...- CH═CH—-...V... —CH═CH— -...Z...- —CO—O— -...Z... —CO—O— -...ZI...- —O—CO—-...ZI... —O—CO— -...K...- —CO— -...K... —CO— -...W...- —CF═CF— -...W...—CF═CF— in which n and m each denote integers, and the three dots “...”are place-holders for other abbreviations from this table.

The following table shows illustrative structures together with theirrespective abbreviations. These are shown in order to illustrate themeaning of the rules for the abbreviations. They furthermore representcompounds which are preferably used.

TABLE D Illustrative structures The illustrative structures arecompounds having three 6-membered rings which are particularlypreferably employed:

The illustrative structures are compounds having four 6-membered ringswhich are particularly preferably employed:

Illustrative structures of dielectrically neutral compounds which arepreferably employed:

Illustrative structures of further compounds which are preferablyemployed:

The following table, Table E, shows illustrative compounds which can beused as stabiliser in the mesogenic media in accordance with the presentinvention. The total concentration of these and similar compounds in themedia is preferably 5% or less.

TABLE E

In a preferred embodiment of the present invention, the mesogenic mediacomprise one or more compounds selected from the group of the compoundsfrom Table E.

The following table, Table F, shows illustrative compounds which canpreferably be used as chiral dopants in the mesogenic media inaccordance with the present invention.

TABLE F

In a preferred embodiment of the present invention, the mesogenic mediacomprise one or more compounds selected from the group of the compoundsfrom Table F.

The mesogenic media in accordance with the present applicationpreferably comprise two or more, preferably four or more, compoundsselected from the group consisting of the compounds from the abovetables.

The liquid-crystal media in accordance with the present inventionpreferably comprise

-   -   seven or more, preferably eight or more, compounds, preferably        compounds having three or more, preferably four or more,        different formulae, selected from the group of the compounds        from Table D.

EXAMPLES

The following examples illustrate the present invention without limitingit in any way.

However, it is clear to the person skilled in the art from the physicalproperties what properties can be achieved and in what ranges they canbe modified. In particular, the combination of the various propertieswhich can preferably be achieved is thus well defined for the personskilled in the art.

Example 1

A liquid-crystal mixture M-1 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 26.0 2 PGIGI-3-CL 8.0 3PGIGI-5-CL 20.0 4 PGIGI-5-F 9.0 5 PPTY-3-4 3.0 6 PYGP-3-5 5.0 7 PYGP-5-35.0 8 CGPC-3-5 3.0 9 CGPC-5-5 5.0 10  CPGP-5-2 8.0 11  CPGP-5-3 8.0 Σ100.0 Physical properties T(N, I) = 171° C. n_(e) (20° C., 589.3 nm) =1.7859 Δn (20° C., 589.3 nm) = 0.2954 ε_(||) (20° C., 1 kHz) = 6.4 Δε(20° C., 1 kHz) = 2.0 γ₁ (20° C.) = 650 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

TABLE 1 Properties of mixture M-1 at 30 GHz T/° C. ε_(r, ⊥) ε_(r, ||)tan δ_(ε r, ⊥) tan δ_(ε r, ||) τ_(ε r) η 11.27 2.40 2.97 0.0109 0.00260.19 17.45 29.71 2.41 2.97 0.0159 0.0037 0.19 11.70 58.28 2.41 2.970.0252 0.0061 0.18 7.07 87.50 2.40 2.89 0.0372 0.0097 0.17 4.51 Note: at20° C., the following is obtained approximately by intrapolation:Δε_(r⊥) = 0.56, tan δ_(ε r, ⊥) = 0.013 and η = 14.5.

For comparison, the compound 4′-pentyl-4-cyanobiphenyl (also called 5CBor K15, Merck KGaA) gives tan δ_(∈r,⊥)=0.026 and η=4.3 at 20° C.

TABLE 2 Comparison of the properties at 30 GHz and 20° C. Example Liquidcrystal Δε_(r⊥) δ_(ε r,⊥) η 1 M-1 0.56 0.013 14.5 2 M-2 0.56 0.014 15Comparison 5CB 0.026 4.3

Example 2

A liquid-crystal mixture M-2 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 26.0 2 PGIGI-3-CL 8.0 3PGIGI-5-CL 20.0 4 PGIGI-5-F 5.0 5 PPTY-3-4 3.0 6 PYGP-4-4 4.0 7 PYGP-5-35.0 8 CCZPC-3-5 3.0 9 CGPC-3-5 3.0 10  CGPC-5-5 5.0 11  CPGP-5-2 8.0 12 CPGP-5-3 8.0 Σ 100.0 Physical properties T(N, I) = 179.5° C. n_(e) (20°C., 589.3 nm) = 1.7861 Δn (20° C., 589.3 nm) = 0.3118

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

TABLE 3 Properties of mixture M-2 at 30 GHz T/° C. ε_(r, ⊥) ε_(r, ||)tan δ_(ε r, ⊥) tan δ_(ε r, ||) τ_(ε r) FoM 11.49 2.41 2.98 0.0108 0.00280.19 17.77 20.29 2.42 2.98 0.0130 0.0033 0.19 14.50 25.02 2.42 2.970.0143 0.0035 0.19 13.08 29.80 2.42 2.97 0.0155 0.0038 0.19 11.99 34.552.42 2.96 0.0169 0.0041 0.18 10.95 58.29 2.41 2.93 0.0246 0.0062 0.187.20 77.56 2.40 2.90 0.0319 0.0087 0.17 5.36 97.57 2.40 2.86 0.04060.0116 0.16 4.00 Note: at 20° C., the following is obtainedapproximately by intrapolation: Δε_(r⊥) = 0.56, tan δ_(ε r, ⊥) = 0.014and η = 15.

Example 3

A liquid-crystal mixture M-3 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-5-CL 20.0 3PPTUI-3-2 20.0 4 PPTUI-3-4 20.0 5 PPTUI-4-4 16.0 6 CPGP-5-2 7.0 7CPGP-5-3 7.0 Σ 100.0 Physical properties T(N, I) = 170.1° C. n_(e) (20°C., 589.3 nm) = 1.5267 Δn (20° C., 589.3 nm) = 0.2918 ε_(||) (20° C., 1kHz) = 7.8 Δε (20° C., 1 kHz) = 4.4 γ₁ (20° C.) = 698 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 4

A liquid-crystal mixture M-4 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-5-CL 19.0 3PPTUI-3-2 18.0 4 PPTUI-3-4 18.0 5 PPTUI-4-4 10.0 6 PGIGP-3-5 6.00 7PPGU-3-F 3.00 8 CPGP-5-2 8.0 9 CPGP-5-3 8.0 Σ 100.0 Physical propertiesT(N, I) = 183.5° C. Δn (20° C., 589.3 nm) = 0.283 ε_(||) (20° C., 1 kHz)= 8.0 Δε (20° C., 1 kHz) = 3.5 γ₁ (20° C.) = 753 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 5

A liquid-crystal mixture M-5 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-5-CL 17.0 3PPTUI-3-2 13.0 4 PPTUI-3-4 13.0 5 PPTUI-4-4 10.0 6 PPGU-3-F 3.0 7PPGU-4-F 3.0 8 PPGU-V2-F 3.0 9 PGIGP-3-5 7.0 10  PGIGP-5-5 7.0 11 CPGP-5-2 7.0 12  CPGP-5-3 7.0 Σ 100.0 Physical properties

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 6

A liquid-crystal mixture M-6 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 17.0 2 PPTUI-3-2 20.0 3PPTUI-3-4 20.0 4 PPTUI-4-4 10.0 5 PPGU-3-F 3.0 6 PPGU-4-F 3.0 7PPGU-V2-F 3.0 8 PGIGP-3-4 5.0 9 PGIGP-3-5 5.0 10  CPGP-5-2 7.0 11 CPGP-5-3 7.0 Σ 100.0 Physical properties T(N, I) = 198.0° C. ε_(||) (20°C., 1 kHz) = 7.7 Δε (20° C., 1 kHz) = 3.5

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 7

A liquid-crystal mixture M-7 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-5-CL 20.0 3PPTUI-3-2 15.0 4 PPTUI-3-4 20.0 5 PPGU-3-F 3.0 6 PPGU-4-F 3.0 7PPGU-V2-F 3.0 8 PGIGP-3-4 5.0 9 PGIGP-3-5 5.0 10  CPGP-5-2 8.0 11 CPGP-5-3 8.0 Σ 100.0 Physical properties T(N, I) = 193.0° C. ε_(||) (20°C., 1 kHz) = 8.7 Δε (20° C., 1 kHz) = 3.5

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 8

A liquid-crystal mixture M-8 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-5-CL 19.0 3PPTUI-3-2 18.0 4 PPTUI-3-4 18.0 5 PPTUI-4-4 10.0 6 PPGU-3-F 2.0 7PPGU-4-F 2.0 8 PPGU-V2-F 2.0 9 PGIGP-3-5 5.0 10  CPGP-5-2 7.0 11 CPGP-5-3 7.0 Σ 100.0 Physical properties

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 9

A liquid-crystal mixture M-9 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 PGP-2-5 10.0 2 PGP-3-4 10.0 3PGP-3-7 15.0 4 PGP-2-2V 5.0 5 PYP-2-2V 10.0 6 PYP-2-4 10.0 7 PYP-2-520.0 8 PYP-3-5 15.0 9 PGIGP-3-5 5.0 Σ 100.0 Physical properties

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 10

A liquid-crystal mixture M-10 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-F 10.0 2 GGP-5-F 10.0 3GGP-3-CL 10.0 4 GGP-4-CL 20.0 5 GGP-5-CL 20.0 6 GGP-6-CL 10.0 7 GGPP-5-35.0 8 PGGP-3-5 5.0 9 PGGP-3-6 5.0 10  PGGP-5-3 5.0 Σ 100.0 Physicalproperties T(N, I) = 134.5° C. n_(e) (20° C., 589.3 nm) = 1.8036 Δn (20°C., 589.3 nm) = 0.2774 ε_(||) (20° C., 1 kHz) = 15.2 Δε (20° C., 1 kHz)= 10.2 γ₁ (20° C.) = 758 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 11

A liquid-crystal mixture M-11 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-F 5.0 2 GGP-3-CL 10.0 3GGP-4-CL 10.0 4 GGP-5-CL 15.0 5 GGP-5-3 20.0 6 PGP-2-5 10.0 7 PGP-3-715.0 8 PGP-2-2V 10.0 9 PGGP-3-5 5.0 Σ 100.0 Physical properties n_(e)(20° C., 589.3 nm) = 1.7885 Δn (20° C., 589.3 nm) = 0.2640 ε_(||) (20°C., 1 kHz) = 8.8 Δε (20° C., 1 kHz) = 4.7 γ₁ (20° C.) = 660 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 12

A liquid-crystal mixture M-12 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 10.0 2 GGP-4-CL 20.0 3GGP-5-CL 20.0 4 GGP-6-CL 10.0 5 GGP-5-3 25.0 6 PGGP-3-5 5.0 7 PGGP-3-65.0 8 PGGP-5-3 5.0 Σ 100.0 Physical properties T(N, I) = 124.5° C. n_(e)(20° C., 589.3 nm) = 1.7951 Δn (20° C., 589.3 nm) = 0.2709 ε_(||) (20°C., 1 kHz) = 11.6 Δε (20° C., 1 kHz) = 6.8 γ₁ (20° C.) = 895 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 13

A liquid-crystal mixture M-13 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-3-CL 5.0 2 GGP-5-CL 19.0 3PGU-7-F 2.0 4 PPTUI-3-2 18.0 5 PPTUI-3-4 18.0 6 PPTUI-4-4 10.0 7PPGU-7-F 2.0 8 PGIGP-3-5 6.0 9 DPGU-3-F 2.0 10  DPGU-3-OT 2.0 11 CPGP-5-2 8.0 12  CPGP-5-3 8.0 Σ 100.0 Physical properties T(N, I) =184.5° C.

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

TABLE 4 Properties of mixture M-13 at 30 GHz T/° C. ε_(r, ⊥) ε_(r, ||)tan δ_(ε r, ⊥) tan δ_(ε r, ||) τ_(ε r) η 9.47 2.51 2.92 0.0094 0.00350.140 15.0 19.67 2.51 2.92 0.0115 0.0041 0.139 12.1 30.07 2.49 2.940.0135 0.0046 0.152 11.2 40.52 2.44 2.96 0.0169 0.0046 0.175 10.3 50.172.36 2.96 0.0214 0.0050 0.204 9.48 59.99 2.34 2.94 0.0246 0.0056 0.2048.24 70.41 2.34 2.93 0.0276 0.0061 0.199 7.22 79.74 2.35 2.91 0.02910.0067 0.195 6.69 84.52 2.35 2.91 0.0295 0.0071 0.192 6.51 Note: at 20°C., the following is obtained approximately by intrapolation: Δε_(r⊥) =2.51, tan δ_(ε r, ⊥) = 0.0115, τ_(ε r) = 0.140 and η = 14.5.

Example 14

A liquid-crystal mixture M-14 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 20.0 2 PGU-3-CL 2.0 3PGU-4-OT 2.0 4 PGP-F-OT 3.0 5 PPTUI-3-2 13.0 6 PPTUI-3-4 15.0 7PPTUI-4-4 20.0 8 PPGU-7-F 2.0 9 PGIGP-3-5 6.0 10  CPTP-3-2 3.0 11 DPGU-3-F 2.0 12  DPGU-3-OT 2.0 13  CPGP-5-2 4.0 14  CPGP-5-3 6.0 Σ 100.0Physical properties T(N, I) = 175.5° C.

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 15

A liquid-crystal mixture M-15 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 10.0 2 GGP-6-CL 5.0 3PGP-3-2V 3.0 4 PGP-2-2V 3.0 5 PPTUI-3-2 15.0 6 PPTUI-3-4 18.0 7PPTUI-4-4 21.0 8 PPGU-7-F 2.0 9 PPGU-V2-F 2.0 10  PGIGP-3-5 7.0 11 CPTP-3-2 4.0 12  CPGU-3-OT 2.0 13  CPGU-4-OT 2.0 14  DPGU-3-OT 2.0 15 CPGP-5-2 4.0 Σ 100.0 Physical properties T(N, I) = 178° C.

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 16

A liquid-crystal mixture M-16 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-CL 20.0 2 GGP-5-3 12.0 3PPTUI-3-2 12.0 4 PPTUI-3-4 16.0 5 PPTUI-4-4 20.0 6 PGUQU-5-F 5.0 7PGGP-3-5 5.0 8 PGGP-3-6 4.0 9 APGP-3-3 3.0 10  APGP-3-4 3.0 Σ 100.0Physical properties T(N, I) = 159.5° C. ε_(||) (20° C., 1 kHz) = 7.9 Δε(20° C., 1 kHz) = 4.3 γ₁ (20° C.) = 686 mPa · s

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

Example 17

A liquid-crystal mixture M-17 having the composition and properties asindicated in the following table is prepared.

Composition Compound No. Abbreviation 1 GGP-5-3 10.0 2 PPTUI-3-F 8.0 3PPTUI-4-F 8.0 4 PPTUI-3-2 12.0 5 PPTUI-3-4 16.0 6 PPTUI-4-4 20.0 7PPTUI-3-A4 5.0 8 PGUQU-5-F 7.0 9 PGGP-3-5 4.0 10  PGGP-3-6 4.0 11 APGP-3-3 3.0 12  APGP-3-4 3.0 Σ 100.0 Physical properties T(N, I) = 169°C.

This mixture is very highly suitable for applications in the microwaverange, in particular for phase shifters.

The invention claimed is:
 1. A liquid-crystal medium, which comprises:at least one compound of the formula I and at least one compound of theformula II and at least one compound of the formula III:

in which L¹¹ denotes R¹¹ or X¹¹, L¹² denotes R¹² or X¹², R¹¹ and R¹²,independently of one another, denote H, unfluorinated alkyl orunfluorinated alkoxy having 1 to 15 C atoms or unfluorinated alkenyl,unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 Catoms, X¹¹ and X¹², independently of one another, denote H, F, Cl, —CN,—NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 Catoms or fluorinated alkenyl, unfluorinated alkenyloxy or unfluorinatedor fluorinated alkoxyalkyl having 2 to 7 C atoms, and

independently of one another, denote

in which L²¹ denotes R²¹ and, in the case where Z²¹ and/or Z²² denotetrans-CH═CH— or trans-CF═CF—, alternatively denotes X²¹, L²² denotes R²²and, in the case where Z²¹ and/or Z²² denote trans-CH═CH— ortrans-CF═CF—, alternatively denotes X²², R²¹ and R²², independently ofone another, denote H, unfluorinated alkyl or unfluorinated alkoxyhaving 1 to 17 C atoms or unfluorinated alkenyl, unfluorinatedalkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, X²¹ andX²², independently of one another, denote F or Cl, —CN, —NCS, —SF₅,fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms orfluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkylhaving 2 to 7 C atoms, one of Z²¹ and Z²² denotes trans-CH═CH—,trans-CF═CF— or —C≡C— and the other, independently thereof, denotestrans-CH═CH—, trans-CF═CF— or a single bond, and

independently of one another, denote

in which L³¹ denotes R³¹ or X³¹, L³² denotes R³² or X³², R³¹ and R³²,independently of one another, denote H, unfluorinated alkyl orunfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl,unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 Catoms, X³¹ and X³², independently of one another, denote H, F, Cl, —CN,—NCS, —SF₅, fluorinated alkyl or fluorinated alkoxy having 1 to 7 Catoms or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy orunfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, Z³¹ toZ³³, independently of one another, denote trans-CH═CH—, trans-CF═CF—,—C≡C— or a single bond, and

independently of one another, denote

and optionally one or more further compounds, provided that theliquid-crystal medium has a birefringence, Δn, at 20° C. and 589 nm, of0.250 or more.
 2. The liquid-crystal medium according to claim 1,wherein the concentration of the compounds of the formula I in themedium is in the range from in total 15% to 70%.
 3. The liquid-crystalmedium according to claim 1, wherein the concentration of the compoundsof the formula II in the medium is in the range from in total 1% to 60%.4. The liquid-crystal medium according to claim 1, which comprises oneor more compounds selected from the group of the compounds of theformulae I-1 to I-3:

in which the parameters have the respective meanings given for formulaI.
 5. A component for high-frequency technology, which comprises aliquid crystal medium according to claim
 1. 6. A component according toclaim 5, which is suitable for operation in the microwave range.
 7. Acomponent according to claim 5, which is a phase shifter.
 8. A processfor the preparation of a liquid-crystal medium according to claim 1,comprising mixing one or more compounds of the formula I with one ormore compounds of the formulae II and one or more compounds of theformula III and optionally with one or more further compounds and/orwith one or more additives.
 9. Microwave antenna array, which comprisesa microwave antenna array incorporating one or more components accordingto claim
 5. 10. A liquid-crystal medium according to claim 1, wherein,in formula II, R²¹ and R²², independently of one another, denote H,unfluorinated alkyl or unfluorinated alkoxy having 3 to 10 C atoms orunfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinatedalkoxyalkyl having 3 to 10 C atoms.
 11. A liquid-crystal mediumaccording to claim 1, wherein the liquid-crystal medium has abirefringence, Δn, at 20° C. and 589 nm, of 0.300 or more.
 12. Aliquid-crystal medium according to claim 1, wherein the liquid-crystalmedium has a birefringence, Δn, at 20° C. and 589 nm, of 0.350 or more.13. A liquid-crystal medium according to claim 1, wherein theliquid-crystal medium has a birefringence, Δn, at 20° C. and 589 nm, offrom 0.250 to 0.90.
 14. A liquid-crystal medium according to claim 1,wherein the liquid-crystal medium has a birefringence, Δn, at 20° C. and589 nm, of from 0.250 to 0.85.
 15. A liquid-crystal medium according toclaim 1, wherein the liquid-crystal medium has a birefringence, Δn, at20° C. and 589 nm, of from 0.250 to 0.80.
 16. A liquid-crystal mediumaccording to claim 1, wherein the liquid-crystal medium has abirefringence, Δn, at 20° C. and 589 nm, of from 0.300 to 0.90.
 17. Aliquid-crystal medium according to claim 1, wherein the liquid-crystalmedium has a birefringence, Δn, at 20° C. and 589 nm, of from 0.300 to0.85.
 18. A liquid-crystal medium according to claim 1, wherein theliquid-crystal medium has a birefringence, Δn, at 20° C. and 589 nm, offrom 0.300 to 0.80.
 19. A liquid-crystal medium according to claim 1,wherein the liquid-crystal medium has a birefringence, Δn, at 20° C. and589 nm, of from 0.350 to 0.90.
 20. A liquid-crystal medium according toclaim 1, wherein the liquid-crystal medium has a birefringence, Δn, at20° C. and 589 nm, of from 0.350 to 0.85.
 21. A liquid-crystal mediumaccording to claim 1, wherein the liquid-crystal medium has abirefringence, Δn, at 20° C. and 589 nm, of from 0.350 to 0.80.
 22. Acomponent for high-frequency technology, which comprises a liquidcrystal medium according to claim
 2. 23. A component for high-frequencytechnology, which comprises a liquid crystal medium according to claim3.
 24. A component for high-frequency technology, which comprises aliquid crystal medium according to claim
 4. 25. A component forhigh-frequency technology, which comprises a liquid crystal mediumaccording to claim
 10. 26. A component for high-frequency technology,which comprises a liquid crystal medium according to claim
 11. 27. Acomponent for high-frequency technology, which comprises a liquidcrystal medium according to claim
 12. 28. A component for high-frequencytechnology, which comprises a liquid crystal medium according to claim13.
 29. A component for high-frequency technology, which comprises aliquid crystal medium according to claim
 14. 30. A component forhigh-frequency technology, which comprises a liquid crystal mediumaccording to claim
 15. 31. A component for high-frequency technology,which comprises a liquid crystal medium according to claim
 16. 32. Acomponent for high-frequency technology, which comprises a liquidcrystal medium according to claim
 17. 33. A component for high-frequencytechnology, which comprises a liquid crystal medium according to claim18.
 34. A component for high-frequency technology, which comprises aliquid crystal medium according to claim
 19. 35. A component forhigh-frequency technology, which comprises a liquid crystal mediumaccording to claim
 20. 36. A component for high-frequency technology,which comprises a liquid crystal medium according to claim
 21. 37. Acomponent for high-frequency technology, which is a phase shifter,varactor, wireless or radio wave antenna array, or matching circuitadaptive filter, which comprises a liquid crystal medium according toclaim
 1. 38. A component for high-frequency technology, which comprisesa cell containing a liquid crystal medium according to claim
 1. 39. Aliquid-crystal medium according to claim 1, wherein the liquid-crystalmedium comprises at least one compound of the formula I wherein X¹² is—NCS, at least one compound of the formula II wherein X²² is —NCS, or atleast one compound of the formula III wherein X³² is —NCS.
 40. Aliquid-crystal medium according to claim 1, wherein the liquid-crystalmedium comprises at least one compound of the formula I wherein X¹² is—NCS or at least one compound of the formula II wherein X²² is —NCS. 41.A component for high-frequency technology, which comprises a liquidcrystal medium according to claim
 39. 42. A component for high-frequencytechnology, which comprises a liquid crystal medium according to claim40.
 43. A liquid-crystal medium according to claim 1, wherein the totalconcentration of compounds of formula I in the liquid crystal medium is20-40% by weight and the total concentration of compounds of formula IIin the liquid crystal medium is 40-70% by weight.
 44. A liquid-crystalmedium according to claim 1, wherein the total concentration ofcompounds of formula I in the liquid crystal medium is 25-35% by weightand the total concentration of compounds of formula II in the liquidcrystal medium is 40-70% by weight.
 45. The liquid-crystal mediumaccording to claim 1, wherein the total concentration of compounds offormulae I, II and III in the liquid crystal medium is 60% by weight ormore.
 46. The liquid-crystal medium according to claim 1, whichadditionally comprises one or more compounds of the following formulae:

in which n denotes an integer in the range from 0 to
 7. 47. Theliquid-crystal medium according to claim 4, which additionally comprisesone or both of the following compounds:


48. The liquid-crystal medium according to claim 4, which comprises oneor more compounds of the formula I-2 which are selected from compoundsof the following formulae:


49. The liquid-crystal medium according to claim 1, which comprises oneor more compounds of the formula II which are selected from compounds ofthe following formulae:


50. The liquid-crystal medium according to claim 1, which comprises oneor more compounds of the formula III which are selected from compoundsof the following formulae:

in which: X³² denotes H, F, Cl, —CN, —NCS, —SF₅, fluorinated alkyl orfluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl,unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinatedalkoxyalkyl having 2 to 7 C atoms, R³¹ has the meaning indicated inclaim 1, n denotes 1 to 7, and z denotes 0, 1, 2, 3 or 4,

in which R³¹ and R³² has the meaning indicated in claim 1, n and m,independently of one another, denote an integer in the range from 0 to15, and z denotes 0, 1, 2, 3 or 4.